add jsdoc tags from jsdoc v3.2-dev AND remove deprecated tags

I also submitted pull request #82 as an alternative to this one.  Take your pick. :)

I've updated the syntax file to bring the JSDoc keywords up to date with the HEAD revision of jsdoc.

This file defines all the jsdoc tags: https://github.com/jsdoc3/jsdoc/blob/master/lib/jsdoc/tag/dictionary/definitions.js

Some keywords have been removed from jsdoc, and this pull request DOES remove deprecated jsdoc keywords.  I submitted pull request #82 which does not remove any keywords.

This pull request removes these deprecated tags: 
 - addon
 - api
 - base
 - beta
 - exec
 - field
 - fileOverview
 - link
 - methodOf
 - optional
 - project
 - title

And adds these tags:

 - abstract
 - callback
 - classdesc
 - defaultvalue
 - desc
 - emits
 - enum
 - external
 - fires
 - instance
 - listens
 - method
 - mixes
 - mixin
 - summary
 - this
 - todo
 - typedef
 - undocumented
 - var
 - variation
 - virtual